Variation in Molecular Species of Core Lipids from the Order Thermoplasmales Strains Depends on the Growth Temperature

Abstract

The order Thermoplasmales includes the wall-less strains in the Archaea. The genus Thermoplasma (two species), the genus Picrophilus (two species), and the genus Ferroplasma (one species) are present. The strains of Thermoplasma include the thermophilic acidophile (T. acidophilum grows between 45 and 62 , optimum 59 , pH 1~4, optimum 1~2 (1); T. volucanium does between 33 and 67 , optimum 60 , pH 1~4, optimum 2 (2)) and the cells are surrounded by a single triple-layer membrane, 5~10 nm thick. The family Picrophilaceae is the thermophilic hyperacidophile growing between 47 and 65 and between pH 0 and 3.5. This family is separated from the family Thermoplasmaceae based on their base sequence of the 16S rRNA gene, DNA-dependent RNA polymerase, and the presence of an S-layer (3). In contrast to these families, the family Ferroplasmaceae, also a wall-less Eur-yarchaeon, grows in the quite different temperature range between 15 and 45 , optimum 35 , pH 1.3~2.2, optimum 1.7 (4). Among these wall-less representatives, only the structure of the membrane lipids of T. acidophilum has been well investigated. The structure of the main membrane lipids of T. acidophilum is caldarchaeol (2, 2 , 3, 3-tetra-O-di(biphytanyl)-sn-diglycerol) (5, 6), one of the ether core lipids of the archaeal strains. Five types of molecular species of the C 40 isoprenoid chain, classified by the number of cyclopentane rings, have been detected in the caldarchaeol of the extreme thermophilic Crenarchaeon such as Sulfolobus solfataricus. These are acyclic-, monocyclic-, bicyclic-, tricyclic-, and tetracyclic-C 40 isoprenoid chains (7). It has been observed that a decrease in the number of double bond in the membrane depends on lowering the environmental temperature for controlling the membrane fluidity in Eucarya and Bacteria. In S. solfataricus, it has been

Archaeal and Bacterial Glycerol Dialkyl Glycerol Tetraether Lipids in Hot Springs of Yellowstone National Park

“…In cases where the group I Crenarchaeota are the dominant source for these GDGTs, such as in most marine environments and certain lake environments, it was shown that the relative distribution of GDGTs I to VI is controlled predominantly by temperature, i.e., with increasing temperature, there is an increasing amount of GDGTs with cyclopentyl moieties (43,50). A similar phenomenon has been demonstrated for hyperthermophilic archaea (10,14,61,62).In addition to these archaeal GDGTs, analysis of soils and peats revealed the abundant presence of GDGTs with nonisoprenoid carbon skeletons (GDGTs XII to XVI) (19,49,72,73). Based on the stereochemistry of the glycerol group and their environmental distribution, Weijers et al (72) showed that they are not derived from archaea but are produced by anaerobic bacteria.…”

“…In cases where the group I Crenarchaeota are the dominant source for these GDGTs, such as in most marine environments and certain lake environments, it was shown that the relative distribution of GDGTs I to VI is controlled predominantly by temperature, i.e., with increasing temperature, there is an increasing amount of GDGTs with cyclopentyl moieties (43,50). A similar phenomenon has been demonstrated for hyperthermophilic archaea (10,14,61,62).…”

Factors Controlling the Distribution of Archaeal Tetraethers in Terrestrial Hot Springs

“…However, when values of TEX 86 are calculated from GDGTs from cultured Crenarchaeota (50,51;Boyd et al,unpublished) and are compared to marine environmental samples, the slopes of these temperature relationships are not the same. If universal, the TEX 86 relationship would require that GDGT-1 disappear above 36 to 48°C (42,43), and thus its presence in cultures and geothermal springs above 65°C (Table 1) (36,61) indicates that other environmental or community variables also influence archaeal GDGT distributions.…”

“…Here we attempted to minimize any such bias by limiting the analysis to samples in which a minimum of five (and usually six or seven) of the nine GDGTs could be identified, with one exception (Monarch Geyser; just three GDGTs). The same criterion was not applied to the cultured samples, as we believe the limited GDGT distributions observed in these samples are real (6,11,16,32,50,51;Boyd et al,unpublished).…”

“…GDGTs have biphytanyl core lipids with zero to as many as four cyclopentyl rings and zero or one cyclohexyl ring on each side chain (41). Some studies of both pure cultures of Crenarchaeota (11,16,50,51;Boyd et al,unpublished) and of environmental samples (39,42,43,58) show that the number of rings increases with growth temperature, while other studies focusing on different species or environmental settings show that this relationship is weaker or apparently absent (6,36,45,61). Because the increased number of cyclopentyl rings also has been shown experimentally (14,32;Boyd et al,unpublished) and through surveys (17,32,57;Boyd et al,unpublished) to be a response to increased acidity (lower pH), it is likely that multiple variables play significant roles when adjusting archaeal membranes to cope with environmental and energetic stresses (52,53).…”